Conductive articles of intractable polymers method for making

ABSTRACT

Conducting articles such as fibers, films, tapes and the like are fabricated from intractable conducting polymers such as polyacetylene. The articles are prepared by (a) forming a gel of a carrier polymer in a compatible solvent, (b) polymerizing, within the gel, a selected monomer, and (c) doping the article so provided. The articles are highly electrically conductive as well as mechanically quite strong.

This invention was made with Government support under Grant Contract No.N00014-83-K-0450 awarded by the Department of the Navy. The Governmenthas certain rights in this invention.

FIELD OF THE INVENTION

This invention relates generally to conducting polymers, and moreparticularly relates to shaped articles such as fibers, tapes, rods andfilms which may be formed from conducting, normally "intractable",polymers.

BACKGROUND OF THE INVENTION

With the discovery of conducting polymers about ten years ago, thepossibility of combining the important electronic properties ofsemiconductors and metals with the attractive mechanical properties andprocessing advantages of copolymers was proposed. Without exception,however, the initial conducting polymer systems were insoluble,intractable, and non-melting (and thus not processable) with relativelypoor mechanical properties. Specific examples of intractable conductingpolymers with attractive electronic properties are polyacetylene.((CH)_(x)), and polyparaphenylene, (C₆ H₄)_(x). These two systems havethe highest density of pi electrons, and both can be doped either p-type(oxidation) or n-type (reduction). Other well-known examples are"polyaniline", or poly(paraphenyleneimineamine) (PPIA), and polypyrrole,which are air stable.

The class of conducting polymers has been enlarged, and a goodunderstanding of the fundamental molecular features which are necessaryto achieve and control the electronic properties of these polymers hasbegun to develop. Soluble conducting polymers have been developed (i.e.,soluble either in water or in common organic solvents), and initialattempts at processing from solution have proven successful. Majorimprovements have been made in material quality and in environmentalstability as well as in the achievement of highly oriented(chain-aligned) materials. Based on this progress, there is every reasonto believe that these materials will continue to evolve to the pointwhere they can be used in a wide variety of technological applications.A number of potentially important application areas have already beenidentified, including use as anisotropic electrical conductors, use innovel electrochemical applications, and use in the exploitation ofnonlinear optical phenomena.

Progress has been made toward rendering specific systems soluble andthereby processable. For example, the poly(3-alkylthiophene) derivatives(P3ATs) of polythiophene are generally soluble and have been processedinto films and fibers. See, e.g., Hotta, S., et al., Macromolecules20:212 (1987); Nowak, M., et al., Macromolecules (in press); Hotta, S.,et al. Synth. Met. (in press); Elsenbaumer, R. L., et al. Synth. Met.15:169 (1986); Polym. Mat. Sci. Eng. 53:79 (1985); and Sato, M., et al.,J. Chem. Soc. Chem. Commun. 83 (1986). However, the enhanced solubilitywas achieved by adding relatively long alkyl chains onto the polymerbackbone, on the 3-position of the thiophene ring. The recentlydiscovered water-soluble self-doped conducting polymers (see Patil, A.O., et al., J. Amer. Chem Soc. 109:1858 (1987); and Patil, A. O., etal., Synth. Met., in press) also achieve solubility throughfunctionalizing at the 3-position of the thiophene ring with therelatively bulky (CH₂)_(n) SO₃ group. Other related examples exist.

Although important, these soluble conducting polymers also have a numberof inherent disadvantages. Films, fibers, and the like formed from thesepolymers have a lower density of pi electrons. They also have reducedinterchain electron transfer integrals, and the monomers have a highermolecular weight due to the addition of the flexible side group. Sincethe density of pi electrons is a critical parameter in determining theelectronic properties of a material, ranging from the material'selectrical conductivity to its nonlinear optics, the pi electron densityshould be maximized. Also, because macroscopic electrical properties arelimited by the ability of electrons to move from chain to chain,interchain transfer should actually be optimized. As the energy densityof a polymer battery electrode decreases with the addition ofnonconjugated side-groups, these soluble systems will inherently havelower energy density. As a result, the electronic properties of thesoluble conducting polymers are quite limited relative to theaforementioned intractable systems. For example, the higher electricalconductivity reported for doped films of the P3ATs is about 100 S/cm,whereas unoriented polyacetylene can be prepared with a conductivity ofat least 2000 S/cm; for oriented materials, values in excess of 10⁵ S/cmhave been reported (Naarmann, H., Synth. Met. 17:2233 (1987); Naarmann,H., Symposium on "Conducting Polymers: Their Emergence and Future",Amer. Chem. Soc. Meeting, Denver, Colo., Apr. 8-9, 1987, in whichconductivity of 1.5×10⁵ S/cm was reported for iodinedopedpolyacetylene). Thus, although processing from solution offers someadvantages, it has limited applicability within the class of conductingpolymers, as degradation of many electronic properties would result.

As an alternative to the soluble conducting polymer systems, shapedarticles such as fibers, tapes and the like fabricated from intractableconducting polymers are generally unknown, and yet would be highlydesirable in a wide range of technological applications. If, inaddition, such shaped articles could be made with the polymer chainshighly oriented along the draw direction, the resulting conductingpolymers would be expected to be highly anisotropic with the desiredelectrical, optical, and nonlinear optical properties principally alongthe orientation direction.

To this end, alternative methods of synthesizing polyacetylene have beenexplored. The synthesis developed at Durham University (so-called Durhampolyacetylene) offers particular advantages in that a soluble andprocessable prepolymer is converted to polyacetylene as a final step(Feast, W. J. in ref. 1, Chapter 1, Vol. 1; Bott, D. C., et al., Mol.Cryst. Liq. Cryst. 117:95 (1985); Kahlert, H., et al., Mol. Cryst. Liq.Cryst. 117:1 (1985)). The Durham polyacetylene can be prepared asamorphous material, or it can be stretch-oriented simultaneously withconversion and isomerization into highly anisotropic free-standingfibers or films. A gel phase of the processable precursor polymer hasbeen used to produce fibers which were subsequently converted topolyacetylene. The resulting materials, however, had limited utility(e.g., maximum conductivity after doping of only 30 S/cm). Moreover,although the resulting Durham polyacetylene can be made so that it is ahighly oriented material, it has specific disadvantages which limit itspotential utility. The fibrillar morphology is not present in Durhampolyacetylene; this material has a high density with no microstructurevisible by electron microscopy. Consequently, the doping kinetics ofDurham polyacetylene are extremely slow, limiting the areas of potentialapplication. Furthermore, the electrical conductivity of the resultingmaterial after doping is limited; maximum values in the literature arebelow 1500 S/cm.

Thus, the ability to fabricate electroactive polymers into shapedarticles such as fibers, films and the like remains seriously limited.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to overcome theaforementioned disadvantages of the prior art and, primarily, to provideshaped articles fabricated from normally intractable, conductingpolymers.

It is additionally an object of the present invention to provideoriented fibers, tapes and the like fabricated from intractableconductive polymers.

It is another object of the invention to provide shaped articlesfabricated from composites of intractable conducting polymers, thecomposites having improved electrical and mechanical properties.

It is still another object of the invention to provide oriented fibers,tapes and the like fabricated from oriented composites of intractableconducting polymers.

It is a further object of the invention to provide methods of making theaforementioned shaped articles.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art on examination of thefollowing, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

In one aspect of the invention, shaped conducting articles such asfibers, tapes, rods and films are fabricated from intractable polymers.Initially, a preshaped reaction medium is prepared, e.g., in the form ofa fiber, tape, film, or the like. This is achieved by producing amechanically coherent and stable gel comprised of a relatively minoramount of a "carrier" polymer dispersed within a suitable solvent.Various compounds necessary for the production of the final intractablepolymer, e.g., monomers and catalysts, may be introduced into the geleither (1) after the carrier gel is formed (for example, by diffusion)or (2) prior to gelation, typically by dispersion or dissolution in thecarrier solution. Subsequently, the gel is transformed into the finalproduct by the proper chemical reactions.

Surprisingly, it was found that this procedure yields conductive,mechanically coherent articles formed from normally intractable polymerssuch as polyacetylene.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a colinear four-probe apparatus for conductivitymeasurement; and

FIGS. 2, 3 and 4 show, graphically, the conductivity of apolyacetylene/polyethylene composite fiber prepared according to themethod of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In essence, the present invention involves two steps: (1) formation of acarrier gel; and (2) the polymerization of the intractable polymer.These steps may be carried out consecutively or simultaneously to giveconductive, mechanically coherent articles, as will be described indetail in the following sections. The articles formed by the presentprocess--typically fibers, rods, tapes or films of otherwise intractablepolymers-- are highly electrically conductive, typically having aconductivity of at least about 300 S/cm. The articles are alsomechanically quite strong, generally displaying a tensile strength of atleast 0.2 g/denier.

Definitions:

By an "intractable" or a "normally intractable" polymer is meant apolymer which cannot be dissolved, shaped or melted by conventionalmeans. The articles disclosed herein are formed from polymers which aregenerally regarded as intractable.

A "shaped article" as used herein is intended to mean a mechanicallycoherent object having a defined form, e.g., a fiber, rod, film or tape.The inventiveness of the present process lies in the ability to formshaped articles from conducting polymers that are "intractable".

A "conjugated" polymer as used herein means a polymer having a pielectron network which allows for electron transfer substantiallythroughout its molecular structure.

A polymer "composite" as used herein means an structural admixture oftwo or more polymeric materials which may or may not be covalently boundto one another.

An "oriented" material as used herein is intended to mean a polymericstructure in which individual polymer chains are substantially linearand parallel.

Generally, "flexible chain" polymers are structures which allow for morevariation in bending angle along the chains (characteristic ratio C∞typically less than about 10), while "rigid rod" polymers tend to bestraighter and more highly oriented (characteristic ratio C∞ typicallygreater than about 100) See P. J. Flory, Statistical Mechanics of ChainMolecules, N.Y.: Wiley & Sons--Interscience, 1969, p. 11.

I. Gel Formation

A. Carrier polymers

The criteria for the selection of the carrier polymer are as follows.The material should allow for the formation of mechanically coherentgels at low concentrations, and remain stable in solvents that arecapable of dispersing, absorbing or dissolving the reactants for formingthe final intractable polymer. Low concentrations of carrier polymer arepreferred in order to minimize any negative effect on the properties ofthe final material; however, the concentration of carrier should be highenough, clearly, to allow for gel formation. Preferred carrier polymersare the high molecular weight (M.W.>100,000) flexible chain polymers,such as polyethylene, isostatic polypropylene, poly(ethylene oxide),polystyrene, and the like. Under appropriate conditions, which can bereadily determined by those skilled in the art, these macromolecularmaterials enable the formation of gels from a wide variety of liquids,including water, acids, and numerous polar and nonpolar organicsolvents. Gels manufactured using these carrier polymers have sufficientmechanical strength at polymer concentrations as low as 1%, even as lowas 0.1%, by volume.

Mechanically coherent gels can also be prepared from lower molecularweight flexible chain polymers, but generally, higher concentrations ofthese carrier polymers are then required. Higher concentrations, asnoted above, may have an undesirable effect on the properties of thefinal products.

Exceptions to this rule are gels made from the so-called rigid rodmolecules, such as the aramid polymers, aromatic polyesters, PBT, PBI,etc. These polymers are generally of lower molecular weights (typicallyin the range of 10,000-100,000). Despite these relatively low molecularweights, mechanically coherent gels can be formed from these "stiff"macromolecules at concentrations as low as 1% or even as low as 0.1%.Therefore, aramids, aromatic polyesters, PBT, PBI, etc. are well-suitedfor the purpose of this invention.

Selection of the carrier polymer is made primarily on the basis ofcompatibility with the final intractable polymer and its reactants, aswell as with the solvent or solvents used. For example, formation ofpolar intractable polymers generally require gels of polymers that arecapable of dissolving or absorbing generally polar reactants. Examplesof such gels are those comprised of poly(vinyl alcohol), poly(ethleneoxide), poly-para(phenylene terephthalate), poly-para-benzamide, etc.,and suitable liquids. On the other hand, if the polymerization of thefinal intractable polymer cannot proceed in a polar environment,nonpolar gels are selected, such as those containing polyethylene,polypropylene, poly(tetrafluoro ethylene), poly(butadiene), and thelike.

Turning now to the issue of concentration, it is of crucial importancethat the gel formed from the carrier solution have sufficient mechanicalcoherence for further handling during the formation of the finalintractable polymer. Therefore, the initial concentration of the carrierpolymer generally is selected above about 0.1% by volume, and morepreferably above about 1% by volume. On the other hand, it is notdesirable to select carrier polymer concentrations exceeding 90% byvolume, because this has a diluting effect on the properties of thefinal intractable polymer product. More preferably, the concentration ofthe carrier polymer in the gel is below 50% by volume, and still morepreferably below 25% by volume.

Thus, in the initial step of the present process, a carrier solution isprovided by dissolving a selected carrier polymer in a compatiblesolvent to a predetermined concentration (using the aforementionedguidelines). The solvent is one in which, clearly, the carrier polymeris substantially soluble and which, furthermore, will not in any wayinterfere with the gelation or polymerization process. The carriersolution is formed into the selected shape, e.g., a fiber, tape, rod,film or the like, by extrusion or by any other suitable method. Aftershaping of the carrier solution, (1) gelation is caused to occur; and(2) monomer(s) selected to form the final intractable polymer areintroduced. Either step (1) or step (2) may be performed first.

B. Gelation

Gels can be formed from the carrier solution in various ways, e.g.,through chemical cross-linking of macromolecules in solution, swellingof cross-linked macromolecules, thermoreversible gelation, andcoagulation of polymer solutions. In the present invention, the twolatter types of gel formation are preferred, although under certainexperimental conditions, chemically cross-linked gels may be preferredas carrier gels.

Thermoreversible gelation refers to the physical transformation frompolymer solution to polymer gel upon lowering the temperature of ahomogeneous polymer solution (although in exceptional cases atemperature elevation may be required). This mode of polymer gelationrequires the preparation of a homogeneous solution of the selectedcarrier polymer in an appropriate solvent according to standardtechniques known to those skilled in the art. The polymer solution isextruded or cast into fiber, rod or film form, and the temperature islowered to below the gelation temperature of the polymer in order toform coherent gels. This procedure is well known and is commerciallyemployed, e.g., for the formation of gels of high molecular weightpolyethylene in decalin, paraffin oil, oligomeric polyolefins, etc., asprecursors for highstrength polyolefin fibers and films.

"Coagulation" of a polymer solution involves contacting the solutionwith a nonsolvent for the dissolved polymer, thus causing the polymer toprecipitate. This process is well known, and is commercially employed,for example, in the formation of rayon fibers and films, spinning ofhigh-performance aramid fibers, etc.

In some instances, it is preferred to exchange the solvent from whichthe carrier polymer gel is formed and replace it with another liquid.This liquid exchange is necessary in cases where the formation of thefinal intractable polymer cannot be carried out in the solvent fromwhich the carrier polymer gel is generated.

II. In Situ Polymerization

A. Reactants

Polymerization generally requires (apart from suitable monomers) one ormore catalysts or "initiators" to initiate reaction. Some or all of thereactants necessary for polymerization--i.e., the selected monomers and,typically, a catalyst--can be introduced into the carrier gel at eitherof two stages: (1) after formation of the carrier solution but prior togelation; or (2) after gelation. The monomers are selected so as to givea conducting, pi electron conjugated macromolecule upon polymerization.

Suitable reactants--i.e., monomer and catalyst --are introduced mostconveniently prior to the formation of the carrier gels by dissolvingthem, together with the carrier polymer, in a common solvent.Subsequently, the solution is extruded and gelled, and polymerization isthen carried out.

Some monomers and catalysts are, however, not stable at the temperatureat which the carrier polymer is dissolved or in the solvent which isused to produce the carrier gel. In those instances, the reactants areintroduced into the carrier gel after the latter is formed. In thisembodiment, the preformed carrier gel is soaked in liquid reactants orin solutions or dispersions of the reactants, or is exposed to gaseousreactants. This method requires miscibility of the reactants with theliquid present in the carrier polymer gel.

B. Polymerization

The polymer synthesis reactions suitable for the embodiment of theinvention include Ziegler-Natta olefin (particularly acetylene)polymerization olefin metathesis (particularly acetylene)polymerization, free radical olefin addition polymerization, anionicolefin polymerization, cationic olefin polymerization andoxidative-coupling polymerization (particularly aniline, pyrrole andbenzene). In the latter case, a polar carrier gel (e.g., aramid,polyvinyl alcohol, etc.) would be loaded with ferric chloride (FeCl₃) orammonium persulfate (NH₄)₂ S₂ O₈. Certain condensation polymerizationssuch as polyquinoline formation are also suitable for this invention. Inthe latter case a polar carrier gel (e.g., aramid, polyvinyl alcohol,etc.) would be loaded with P₂ O₅ -enriched polyphosphoric acid.

The present process may be used to prepare conducting articles fromeither homopolymers or copolymers. Thus, in one embodiment, only onetype of monomer is introduced into the carrier gel. In an alternativeembodiment, two or more types of monomers are used to form a copolymer.In either case, the carrier polymer may be allowed to remain in thearticle, forming a composite with the intractable polymeric materialthat is formed from one or more types of monomers. A particularlypreferred composite is a copolymer of polyacetylene and polyethylene,wherein the polyacetylene is the "intractable" polymeric material andthe polyethylene serves as the carrier polymer.

In an alternative embodiment, as will be discussed, the carrier polymermay be removed from the final article after polymerization.

C. Post-Polymerization Treatment

After polymerization, a shaped material is obtained that typicallyincludes, in addition to the intractable polymer, carrier polymer,unreacted monomer, catalyst, and the liquid of the carrier gel, all ofwhich may be removed by washing, extraction and/or evaporation. Ifdesired, as noted above, the carrier polymer may be left in thecomposite to enhance mechanical strength, providing its presence doesnot significantly limit the properties of interest of the final article,e.g., its electrical conductivity. In such a case, the carrier polymercan be removed by extraction with an appropriate solvent.

The shaped article thus fabricated from the intractable polymer isrendered conductive upon either p-type (oxidative) or n-type (reductive)doping, using standard dopants and techniques.

III. Drawing of the Carrier/Polymer Composite

Frequently, it is desirable to subject the carrier polymer/intractablepolymer composite to mechanical deformation, typically by stretching atleast about 100% in length, prior to, during, or after polymerization.Deformation of polymeric materials is carried out in order to orient themacromolecules in the direction of draw, which results in improvedmechanical properties. In the case of electrically conductive polymers,not only do the mechanical properties improve, but, more importantly,the electrical conductivity also displays a drastic enhancement bytensile drawing.

Deformation of the carrier polymer/intractable polymer composite can beperformed either in its as-produced state or after extraction of all orsome of the reactants. Deformation of the as-polymerized compositematerial is advantageous when residual unreacted monomer and/or liquidin the gel act as plasticizers. This will improve deformability and leadto higher molecular orientation and, therefore, enhanced physicalproperties.

IV. Dynamic In Situ Polymerization

During Carrier Gel Drawing

In an alternative embodiment of the invention, polymerization of theintractable material is carried out during deformation of the preformedcarrier gel. This procedure is especially useful for systems comprisingintractable polymers that are not readily post-drawn.

This method of dynamic polymerization during drawing of the carrier gelrequires good deformation characteristics of the latter. Particularlysuitable for this purpose are the thermoreversible gels formed fromultra-high molecular weight (M.W.>1,000,000) carrier polymers. Thesegels exhibit maximum draw ratios (=final sample length/original samplelength) of 60 or more, and may sometimes reach values as high as 300.These exceptionally high draw ratios are very beneficial for thedevelopment of orientation not only of the carrier polymer, but also ofthe intractable polymer, since it is formed during prolongedelongational flow. As a result, the materials produced according to thisprocess have outstanding mechanical and electrical properties.

V. Experimental: Characterization of the Fibers and Films of theInvention

A. Electrical Conductivity Measurements

A four-probe technique for conductivity measurements was used to measurethe conductivities of materials herein. FIG. 1 shows a typical colinearfour-probe configuration. The four contacts (labeled 1, 2, 3 and 4) aremade on the surface of sample 5 in a linear array. A current (I) ispassed through probes 1 and 4 and the voltage drop (V) across probes 2and 3 is measured. The voltage measurement is usually carried out bymeans of a high impedance voltmeter and is considered to be essentiallya zero-current measurement. Hence, the contact resistance between probes2 and 3 is measured. The voltage measurement is usually carried out bymeans of a high-impedance voltmeter and is considered to be essentiallya zero-current measurement. Hence, the contact resistance between probes2 and 3 and the sample is minute since the current flow through thevoltmeter is minute. Ohmic contacts were carried out using "Electrodag"contacts (3M Co., Minneapolis, Minn.) in which platinum electrodes wereattached to the fiber or tapes by means of Electrodag 502--a suspensionof finely divided graphite in methyl ethyl ketone. The resistance (R) ofthe fibers was first measured by the four-probe technique. The length(L) was measured with a ruler, and the cross-sectional area (A) wasmeasured using a scanning electron microscope. The conductivity of thefiber was then calculated by the equation Conductivity=(L/AR).

B. Calorimetric Measurements

The composite materials of the invention were tested using adifferential scanning calorimeter (Mettler DSC TA3000). Samples of about4 mg were used. The heating rate was 10° C./min. Melting temperaturesand enthalpies of fusion were measured according to standard techniques.Where appropriate and possible, the enthalpy of fusion of the sampleswas employed to determine the quantity of the carrier polymer in thecomposite.

C. Mechanical Properties

The mechanical properties of the various materials described in theexamples were tested at room temperature using an Instron Tensile Testermodel 1122. The initial length of the test specimens was 10 mm, and thecross-head speed was 10 mm/min. The modulus of the fibers was taken tobe the initial, or Young's, modulus. Cross-sectional areas of the fiberswere measured by scanning electron microscopy on fractured samples. Thedenier (linear density) of the samples was measured by weighing 100 mmof the fibers.

It is to be understood that while the invention has been described inconjunction with the preferred specific embodiments thereof, that theforegoing description as well as the examples which follow are intendedto illustrate and not limit the scope of the invention. Other aspects,advantages and modifications within the scope of the invention will beapparent to those skilled in the art to which the invention pertains.

EXAMPLE 1

A. Preparation of Catalyst

Ten ml of the solvent decalin (decahydronaphthalene, Fisher Scientific)were poured into a 50 ml three-neck flask. The solvent was frozen atliquid nitrogen temperature and degassed under vacuum (<3×10⁻⁶ mm Hgpressure) for 2 minutes. Subsequently, the decalin was thawed at roomtemperature. This degassing procedure was repeated three times.

Then, 3.1 ml of Al(C₂ H₅)₃ was added to the degassed decalin under anargon blanket. Next, 4.1 ml of Ti(OC₂ H₉)₄ was added to the solutiondrop by drop over a period of 7 min, again under a blanket of argon. Themixture was stirred for 1 hour at a temperature of 88° C. under argon.Finally, the homogeneous catalyst solution was cooled down to roomtemperature.

B. Preparation of Gel

Ten ml of decalin were mixed, at room temperature, with 8.6 mg ofultra-high molecular weight polyethylene (Hostalen GUR 412, Hoechst) ina 50 ml three-neck flask. This mixture was degassed according to theprocedure described in A. Subsequently, the degassed mixture was heatedat a temperature of 160° C. for 45 minutes while stirring under an argonblanket. A viscous solution was obtained.

A glass tube with an inner diameter of 20 mm and a length of 400 mm wasconnected to the flask, and a liquid fiber was drawn from thepolyethylene solution into the tube. The liquid fiber rapidly cooled toambient temperature and formed a gel filament. This operation wascarried out under a flow of argon. Subsequently, the glass tube wasclosed and transferred and attached to the three-neck flask thatcontained the catalyst. The flask was tilted, which caused the gel fiberto be contacted with the catalyst solution. The gel was soaked at roomtemperature in this solution for a period of 1 hour. The excess catalystsolution was returned to the three-neck flask.

C. Polymerization

The glass tube containing the polyethylene/catalyst gel fiber wasremoved from the three-neck flask and connected to a vacuum line, whereit is degassed for 5 minutes. Subsequently the gel fiber was exposed to600 Torr of acetylene (monomer) gas for 90 minutes to yield thepolyethylene/polyacetylene composite fiber. After the polymerization wascompleted, the remaining monomer gas was trapped in a container that wascooled with liquid nitrogen. The composite fiber was then degassed undervacuum for 10 minutes.

The glass tube containing the fiber was then transferred into anargon-filled glove bag. The composite fiber was washed to remove thecatalyst with purified toluene until the washing solution remainedcolorless.

The composite fiber was of 420 denier.

The polyacetylene content of the composite fiber was estimated to be 83%by weight, using the calorimetric method described above.

The mechanical properties of the composite fiber were determined to be:

Young's modulus, 6.8 g/den

tensile strength, 0.2 g/den

elongation at break, 75%.

EXAMPLE 2

The polyacetylene/polyethylene composite fiber of Example 1 was doped atroom temperature in a saturated solution of 2.65 g of iodine in 100 mlcarbon tetrachloride for various periods of time. The doped fiber wasdried and its electrical conductivity measured using a 4-probe device.The conductivity of the composite fiber reached a constant value of 450S/cm after doping for about 45 min, as is illustrated in FIG. 2.

EXAMPLE 3

A. Preparation of Catalyst

Ten ml of mineral oil (Fisher Scientific) was poured into a 50 mlthree-neck flask. The solvent was degassed under a vacuum (<3×10⁻⁶ mmHgpressure) for 1 hour.

Then 3.1 ml of Al(C₂ H₅)₃ was added to the degassed mineral oil under anargon blanket. Next 4.1 ml of Ti(OC₄ H₉)₄ was added to the solution dropby drop over a period of 7 minutes, again under a blanket of argon. Themixture was stirred for 1 hour at a temperature of 88° C. under argon.Finally, the homogenized catalyst solution was cooled down to roomtemperature.

B. Preparation of Gel

Ten ml of mineral oil was mixed, at room temperature, with 8.6 mg ofultra-high molecular weight polyethylene (Hostalen GUR 412, Hoechst) ina 50 ml three-neck flask. This mixture was degassed according to theprocedure described in A. Subsequently, the degassed mixture was heatedwhile stirring under an argon blanket for 45 minutes at a temperature of160° C. A viscous solution was obtained. This solution was transferredinto a laboratory-scale fiber-spinning apparatus. A polyethylene gelfiber was spun according to standard procedures.

C. Polymerization

The as-spun polyethylene gel fiber was transferred to the catalystsolution and soaked for 1 hour at room temperature. Thepolyethylene/catalyst gel fiber was inserted in a container, degassedand then exposed to 51 cm Hg pressure of acetylene gas. The resultingpolyacetylene/polyethylene composite fiber was washed with toluene untilthe washing solution became colorless. Subsequently, it was washed withmethanol/5% HCl solution for 50 minutes and then for 30 minutes withmethanol. Finally, the composite fiber was dried under a flow of argonand then under vacuum. The final fiber was doped according to thetechnique described in Example 2 and its electrical conductivitymeasured. It was found that the conductivity reached a maximum value of1200 S/cm after about 1 hour of doping, as illustrated in FIG. 3.

The composite fiber was of 390 denier.

The polyacetylene content of the composite fiber was estimated to be 82%by weight, using the calorimetric method described above.

The mechanical properties of the composite fiber were determined to be:

Young's modulus, 3.5 g/den

tensile strength, 0.7 g/den

elongation at break, 170%

EXAMPLE 4

Example 3 was repeated, except that, before the washing procedure, theas-polymerized composite fiber was drawn at room temperature, in argon,to 2.2 times its original length using a laboratory stretching frame.Subsequently, the drawn fiber was washed according to the procedure inExample 3. The final fiber was doped according to the techniquedescribed in Example 2, and its electrical conductivity measured. It wasfound that the conductivity reached a maximum value of 6000 S/cm after 1hour of doping, as illustrated in FIG. 4.

The drawn composite fiber was of 180 denier. Its mechanical propertieswere determined to be:

Young's modulus, 6 g/den

tensile strength, 2.1 g/den

elongation at break, 50%.

EXAMPLE 5

A. Preparation of PPTA gel:

Poly-para (Phenyleneterephthalamide) (PPTA, Kevlar® from DuPont ofWilmington, Del.) was prepared as follows 71.6 g of (97%) sulfuric acidwas mixed with 1.07 g (PPTA) under stirring for 2 days at roomtemperature in a 250 ml flask. A viscous solution was obtained. Thissolution was transferred into a 0.75 oz syringe. The PPTA solution wasspun using a syringe, to form a gel fiber, into a 1.2 N solution ofaniline in 1 N HCl. The gel fiber was left for 2 hours to absorb theaniline monomer.

B. Polymerization

This PPTA/aniline gel fiber was transferred into an aqueous 0.025 N(NH₄)₂ S₂ O₈ solution and the monomer was allowed to polymerize for 2hours. The resulting PPTA/polyaniline composite fiber was washed with 1N H₂ SO₄ solution, and then dried under vacuum for 24 hours. Theelectrical conductivity of said PPTA/polyaniline fiber was 0.3 S/cm.

This example illustrates the use of rigid chain molecules as carrierpolymers. The PPTA had a M_(w) of 40,000; C∞=124.

We claim:
 1. A process for making electrically conductive shapedarticles of intractable conjugated polymeric materials, the processcomprising the steps of:(a) providing a carrier solution by dissolvingin a compatible solvent(i) a predetermined amount of a monomer selectedto form an intractable conjugated polymer upon polymerization, whereinsaid polymer is polyacetylene or polyaniline, (ii) an amount of apolymerization initiator effective to catalyze polymerization of saidmonomer, and (iii) about 0.1 wt. % to about 50 wt. % of a carrierpolymer selected from the group consisting of flexible chain polymershaving a molecular weight greater than about 100,000, rigid chainpolymers having a molecular weight between about 10,000 and about100,000, and mixtures thereof; (b) forming said carrier solution intothe shape of the selected article; (c) treating said carrier solution soas to cause gelation, thereby providing a carrier gel; (d) causingpolymerization of said monomer to give a shaped article of polymerizedgel; and (e) rendering the shaped article conductive through p-type orn-type doping.
 2. The process of claim 1, wherein said conductivearticle is a fiber.
 3. The process of claim 1, wherein said conductivearticle is a rod.
 4. The process of claim 1, wherein said conductivearticle is a film.
 5. The process of claim 1, wherein said conductivearticle is a tape.
 6. The process of claim 1, wherein said carrierpolymer is present in an amount between about 1.0 wt. % and about 25 wt.%.
 7. The process of claim 1, wherein said carrier solution containsmore than one monomer and said polymerization yields a copolymer.
 8. Theprocess of claim 1, wherein gelation is effected by coagulation.
 9. Theprocess of claim 1, wherein gelation is effected by cross-linking saidcarrier polymer.
 10. The process of claim 1, wherein gelation iseffected thermoreversibly.
 11. The process of claim 1, wherein saidcarrier polymer is removed after polymerization.
 12. The process ofclaim 1, wherein said intractable polymer is polyacetylene.
 13. Theprocess of claim 12, wherein said carrier polymer is polyethylene andsaid shaped article is a composite of polyacetylene and polyethylene.14. The process of claim 1, wherein said intractable polymer ispolyaniline.
 15. The process of claim 14, wherein said carrier polymeris poly-para(phenyleneterephthalamide) and said shaped article is acomposite of polyaniline and poly-para(phenyleneterephthalamide). 16.The process of claim 1, wherein said carrier gel is stretched at leastabout 100% in length prior to polymerization.
 17. The process of claim1, wherein said carrier gel is stretched at least about 100% in lengthduring polymerization.
 18. The process of claim 1, wherein saidconductive article is stretched at least about 100% in length afterpolymerization.
 19. A process for making electrically conductive shapedarticles of intractable conjugated polymeric materials, the processcomprising the steps of:(a) providing a carrier solution by dissolvingin a compatible solvent about 0.1 wt. % to about 50 wt. % of a carrierpolymer selected from the group consisting of flexible chain polymershaving a molecular weight greater than about 100,000, rigid chainpolymers having a molecular weight between about 10,000 and about100,000, and mixtures thereof; (b) forming said carrier solution intothe shape of the selected article; (c) treating said carrier solution soas to cause gelation, thereby providing a carrier gel; (d) introducinginto said carrier gel:(i) a predetermined amount of a monomer selectedto form an intractable conjugated polymer upon polymerization whereinsaid polymer is polyacetylene or polyaniline, and (ii) an amount of apolymerization initiator effective to catalyze polymerization of saidmonomer; (e) causing polymerization of said monomer to give a shapedarticle of polymerized gel; and (f) rendering the shaped articleconductive through p-type or n-type doping.
 20. The process of claim 19,wherein said conductive article is a fiber.
 21. The process of claim 19,wherein said conductive article is a rod.
 22. The process of claim 19,wherein said conductive article is a film.
 23. The process of claim 19,wherein said conductive article is a tape.
 24. The process of claim 19,wherein said carrier polymer is present in an amount between about 1.0wt. % and about 25 wt. %.
 25. The process of claim 19, wherein saidcarrier solution contains more than one monomer and said polymerizationyields a copolymer.
 26. The process of claim 19 wherein gelation iseffected by coagulation.
 27. The process of claim 19, wherein gelationis effected by cross-linking said carrier polymer.
 28. The process ofclaim 19, wherein gelation is effected thermoreversibly.
 29. The processof claim 19, wherein said carrier polymer is removed afterpolymerization.
 30. The process of claim 19, wherein said carrierpolymer is allowed to remain after polymerization, thus providing aconductive article comprising a composite of said carrier polymer andsaid intractable polymer.
 31. The process of claim 19, wherein saidintractable polymer is polyacetylene.
 32. The process of claim 31,wherein said carrier polymer is polyethylene and said shaped article isa composite of polyacetylene and polyethylene.
 33. The process of claim19, wherein said carrier gel is stretched at least about 100% in lengthprior to polymerization.
 34. The process of claim 19, wherein saidcarrier gel is stretched at least about 100% in length duringpolymerization.
 35. The process of claim 19, wherein said conductivearticle is stretched at least about 100% in length after polymerization.36. The process of claim 19, wherein said intractable polymer ispolyaniline.
 37. The process of claim 36, wherein said carrier polymeris poly-para(phenyleneterephthalamide) and said shaped article is acomposite of polyaniline and poly-para(phenyleneterephthalamide).